The revelation came with the release of court documents relating to a case against a New York woman. She is accused of sharing 1000 songs through a peer-to-peer file network, using the online pseudonym "nycfashiongirl". She claims to have made the MP3 files found on her computer from CDs that she owned.
The RIAA says the username of another computer user was found in the header of one of the MP3s. Headers are routinely used to store a song's title and length, but some MP3 compression software may also add information such as the username of the person who created the file.
Read More: NewScientist.